The present invention relates to a stitch pressing device for flat V-bed knitting machine. More particularly, it relates to a stitch pressing device provided in a flat V-bed knitting machine of the type having a pair of needle beds arranged in an inverted-V pattern with a gap formed therebetween so as to permit the needles of the needle beds to cross each other in the course of their upward movement and having a carriage reciprocably movably arranged above the needle beds and comprising a pair of cam boxes integrally connected to each other, each cam box being provided with knitting cams which act on the needles during knitting operation, wherein the stitch pressing device permits the formed stitches to descend from a knockover comb without weights or a take-down mechanism being provided below the gap between the needle beds to pull the stitches downward.
Various stitch pressing devices are known which are designed to perform such function. They may be broadly classified into two types. One type is of V-shape when viewed in front elevation. It is generally such that on the carriage there are provided a pair of lateral members bridging the two cam boxes, front and rear, of the carriage, a support member spanning the lateral members, and arms swingable along the length of the needle beds and supported on the support member, and a V-shaped stitch pressing device is attached at the middle portion thereof to the lower end of each arm. In a flat knitting machine employing a stitch presser of this type, the arm is caused to swing at the point of reversal of the movement of the carriage so that the left half part of the V-shaped stitch presser is brought in sliding contact with the stitches being formed during the rightward travel of the carriage and the right half part of the stitch presser is brought into slide contact with the stitches during the leftward travel of the carriage, thus stitch pressing is effected throughout the movement of the carriage. Stitch pressing devices of such swingable V-shaped type are disclosed, for example, in the U.S. Pat. Ser. No. 3,839,884, U.S. Pat. Ser. No. 3,842,623, and U.S. Pat. Ser. No. 4,027,504.
The other type is such that the stitch presser comprises a pair of L-shaped single-way stitch pressing means, one provided on one of the cam boxes and adapted to enter into the gap between the needle beds for sliding contact with the knitted fabric during the movement of the carriage in one direction only and the other provided on the other cam box and adapted to enter into the gap for sliding contact with the knitted fabric during the movement of the carriage in the opposite direction. Coming within the category of this type is, for example, one previously developed by the present inventor (which is disclosed in the specification of Published unexamined Japanese Utility Model Application No. 54-139748).
These known stitch pressers have their disadvantages as well as advantages, as pointed out below.
The V-shaped stitch presser swingable for changeover movement as disclosed in U.S. Pat. Ser. No. 3,842,623, for example, has an advantage that it does not require overrun of the carriage beyond the length of needle bed in order to allow swinging of the stitch presser.
In order that it may be held in operative position, however, the V-shaped stitch presser is provided with a pair of lateral members bridging the front and rear cam boxes, a support extending between the lateral members, and arms swingably carried by the support; these elements move back and forth in synchronism with the carriage, occupying the space above the clearance between the needle beds. In a flat knitting machine to which this type of stitch presser is applied, therefore, it is necessary that the space above and over the full length of the gap between the needle beds must be open at all times for the passage of the support and the arms extending downwardly from the support.
As such, where this type of stitch presser is employed in flat knitting machines, the difficulty is that no space is available right above the gap for provision of yarn guide rails for yarn carrier means or for movement of yarn guide levers. Especially in a novelty pattern knitting machine which requires as many yarn guide levers as possible, this is very inconvenient because it limits the numbers of yarn guide rails and yarn guide levers to be provided.
Another difficulty with the known stitch pressers of V-shape type is that the non-operating side of the stitch presser during the movement of the carriage in either direction is always kept projecting diagonally upward above the gap between the needle beds and in the direction of movement of the carriage; since the stitch presser is larger in width than the arm to which it is mounted, the non-operating side of the stitch presser is liable to contact a yarn guide lever in rest position during the movement of the carriage, thus causing troubles.
The L-shape type stitch pressing device has an advantage over the V-shape type in this respect. As above mentioned, one known pressing device of this type has two L-shaped stitch pressers individually mounted on the cam boxes, one movable in its operative position during the movement of the carriage in one direction and the other movable in its operative position during the movement of the carriage in the opposite direction. The L-shaped stitch presser comprises a base portion corresponding to the upper end of vertical portion of "L", mounted on a support provided on a cam box above one of the needle beds, a portion corresponding to the vertical portion of "L", disposed in a downward facing position in substantial parallelism with the needle tricks of the other needle bed, said vertical portion being downwardly inclined toward its end, a horizontal front portion, said front portion being adapted to enter into and retract from the gap between the needle beds to take an advanced position (operative position) and a retracted position (inoperative position), said advanced position covering an area extending laterally within the gap, said retracted position being a position close to the upper-side surface of the needle bed below the cam on which the stitch presser is mounted and not in the way of needles moving upward from the opposite needle bed. In this type of stitch pressing device, the space which the pressers occupy above the needle beds is limited to a space of up to slightly above the level of knockover comb.
Unlike the V-shape presser type wherein the pressers are adapted to swing in the gap between the needle beds, therefore, the L-shape presser type has an adavantage that the open space above the gap can be fully utilized for provision of yarn-guide carrier means so that a greater number of yarn guide levers are allowed to run in the space.
In known stitch pressers of the L-shape type, however, the horizontal portion of "L", or operative portion of the presser which comes in slide contact with and exerts pressure upon the formed stitches is movable only along the needle tricks for access into and retraction from the gap between the needle beds or the space between the knockover combs thereof; therefore, the difficulty with this type is that displacement of pressers for changeover requires the overrun of the carriage beyond the length of the needle beds so that the pressers are brought to a position outside the gap between the needle beds for changeover. In other words, known stitch pressers of this type have a disadvantage that the carriage is required to reciprocate its full course of movement (longer than the length of the needle beds) irrespective of the required width of knitting.
The primary object of the present invention is to provide an improved stitch pressing device of the L-shape type which eliminates the disadvantage of known devices of the type while retaining the advantage of such known devices over the known V-shape type stitch pressers and which also has an advantageous feature similar to that of said known V-shape type pressers.
To this end, the present invention contemplates to provide a stitch pressing device of L-shape type comprising stitch pressing means arranged on the carriage and operable in synchronism with the reciprocation of the carriage and at substantially same phases as the operative zones of knitting and transfer locks disposed on the carriage, said stitch pressing means consisting of a pair, one provided on one of the cam boxes on the carriage and having a L-shaped stitch presser bar operable during the movement of the carriage in one direction in manner that its operative portion enters the gap between a pair of needle beds for slide contact with formed stitches and the other provided on the other cam box and having a L-shaped stitch presser bar operable during the movement of the carriage in the opposite direction in manner that its operable portion enters said gap for slide contact with formed stitches, individual operative portions of the pair of stitch pressing means being adapted to be given movement involving a circular motion for passage above the knockover comb so that the operative portions are controllable at a given position above the needle beds for movement between operative and non-operative positions without overrun of the carriage beyond the length of the needle beds.
By imparting to the presser bars such movement involving a circular motion, the displacement of the pair of stitch pressing means between operative and non-operative positions can be controlled at a given position above the needle beds without excessive movement of the carriage. Naturally, however, the possible depth of descent of the presser bar into the gap that may be attained by such movement involving a circular motion is limited. With the stitch pressing device as above proposed, it is impracticable to achieve deep entry into the gap of the operative portion which comes in slide contact with the knitting.
Where a pressing device of such construction is employed, the presser bar thereof may sufficiently press the uppermost row of stitches to force down the fabric being knitted if the uppermost row of stitches hangs across the gap and between needles of the needle beds (as in the case of rib stitches), but if the uppermost row is depending from needles of one needle bed only (as in the case of plain stitches), the presser bar cannot sufficiently force the fabric downward because its entry into the gap is not deep enough.
Further, it is noted that the known stitch pressers, both V-shape and L-shape types, have their operative areas relative to the knitting in substantially same zones as those of knitting locks on the carriage; therefore, the formed rows of stitches are somewhat liable to rise after the passage of the presser, so the provision of a holding-down member is required in order to prevent such rise.
Another object of the invention is to provide a stitch pressing device which has sub-presser means adapted to suitably press down the formed stitches, whether the uppermost row of stitches is hanging between needles of both needle beds or it is hanging from needles of one needle-bed only, and which has said sub-presser means disposed intermediate the individual stitch-pressing means and in the widthwise direction of the carriage so that prevention of stitch rise and holding-down of the knitting can be effectively performed without provision of hold-down means below the gap between the needle beds.
The problems as set forth above have thus been solved. Hence, the stitch pressing device in accordance with the present invention is characterized by: stitch pressing means arranged on a carriage and operable at substantially same phases as the operative zones of knitting and transfer locks on the carriage, sub-presser means disposed on the carriage and operable at different phases from the operative zones of the knitting and transfer locks on the carriage, said stitch pressing means comprising a pair of one-way operable stitch pressing means, one provided on one cam box of the carriage and having a stitch presser bar adapted to enter a gap between a pair of needle beds for slide contact with formed stitches during the movement of the carriage in one direction and the other provided on another cam box of the carriage and having a stitch presser bar adapted to enter said gap between the needle beds for slide contact with formed stitches during the movement of the carriage in the opposite direction, said one-way operable stitch pressing means each comprising a support means mounted on the front top surface of one of the cam boxes, a pair of sliders, upper and lower, individually slidably supported on said support means in substantially parallel relation to the needle tricks of the needle bed below the cam box opposite to the cam box on which said support means is mounted, a stitch-presser-bar mounting block pivotally connected at the base portion thereof to the front end portion of the lower slider and coupled at the upper free end thereof to the front end portion of the upper slider, a stitch presser bar secured at the base portion thereof to the upper end portion of the stitch-presser-bar mounting block, and drive means for said pair of sliders, said stitch presser bar being L-shaped and comprising a portion corresponding to the upper part of the vertical portion of "L" and at which it is secured to said mounting block, a portion corresponding to the lower part of said vertical portion and downwardly inclined toward the mounting block, and a portion corresponding to the horizontal portion of "L" and constituting an operative portion extending longitudinally of said gap between the needle beds, said drive means for the pair of sliders comprising pins individually projecting from the sliders, a pair of cam grooves individually engaging said pins, and a grooved cam plate carried by said support means slidably along the length of the needle beds, said pair of cam grooves having a cam surface for moving said upper and lower sliders to impart movement involving a circular mortion above the knockover comb to the front portion of said stitch presser bar for entry into and retraction from the gap between the needle beds, said sub-presser means comprising a mounting member having its lower end portion pivotally supported at a suitable location on said support means on the cam box and having its upper end portion adapted to move toward and away from a knockover comb, spring means urging the upper end portion of the mounting member in the forward direction, a stopper for stopping the urging force of the spring at a given forward position, and a sub-presser element secured at the base portion thereof to the upper end portion of the mounting member, said sub-presser element having its front end portion downwardly inclined at a point past the space right above the knockover comb and positioned in the gap between the needle beds, said front end portion having on its both sides a sled-shaped arcuate surface extending longitudinally of the needle beds and being constantly urged deeper into the gap than said stitch presser bar.
The stitch pressing means in accordance with the present invention, if provided in plurality on the support means correspondingly to the raising zones of the knitting and transfer locks disposed on each cam box, can effectively press down, by means of the horizontal portion thereof, stitches being formed by the needles as the needles are raised by these locks, thus preventing the stitches from rising.
On each cam box, however, there are provided, correspondingly to the raising zones of the raising cams of the knitting lock, brushes for keeping in open position the latches of needles raised from the opposite-side needle bed by the raising cams, said brushes being positioned with their hair ends facing the knockover comb of the opposite-side needle bed so that they can contact the latches of needles raised from the opposite-side needle bed.
Therefore, where the stitch pressing means according to the invention are disposed at raising zones of the knitting cam and along the width of the carriage, the horizontal portions of presser bars of the stitch pressing means are positioned at same phases as the brushes; accordingly, upon its circular motion above the knockover comb for retraction from its operative position or the gap between the needle bed, the horizontal portion of each presser bar may strike and deform the hair ends of said brush.
Another object of the invention is to provide a stitch pressing device in which the horizontal portion of the stitch presser bar thereof is not liable to damage the hair ends of a brush provided on a cam box during such circular motion thereof.
The stitch pressing device according to this invention. wherein the above object has also been achieved, comprises a brush provided on each cam box at substantially same phase as the horizontal portion of the stitch presser bar in the widthwise direction of the cam box, said brush being mounted to the front end portion of a brush-mounting member slidably carried on said support means in substantial parallelism with the upper and lower sliders, said brush being movable between its operative and non-operative positions relative to the needles of the needle bed on the opposite side, drive means for displacing said brush between the operative and non-operative positions thereof, said drive means including a pin projecting from said brush-mounting member, a cam groove formed on said grooved-cam plate and engaged by said pin, said cam groove having at least a cam surface for retracting said brush from the operative position thereof in synchronism with an early-stage retracting movement of said stitch presser bar.